Yesterday my ext HD (500 GB capacity) was having problems so I looked at its SMART data and it showed 20 sectors pending (and dozens reallocated). I spent the day running a chkdsk /r and it did fix some stuff but when I look at SMART again, I see ~500 sectors pending and ~300 reallocated. For it to increase so quickly is troubling. Could this be because one particular platter/disk/independently manufactured part was defective or does this kind of thing usually result in a dead disk? I should mention that it being an external, I've treated it slightly abusively such as shaking it and dropping it.